HUNTSVILLE, Texas - A Texas inmate convicted in the death of a prison guard has been executed after the U.S. Supreme Court rejected his lawyer's attempts to halt the punishment.

Robert Pruett was given a lethal injection Thursday evening for the December 1999 death of corrections officer Daniel Nagle at a prison southeast of San Antonio. Nagle was repeatedly stabbed with a tape-wrapped metal rod, though an autopsy showed he died from a heart attack that the assault caused.

Prosecutors have said the attack stemmed from a dispute over a peanut butter sandwich that Pruett wanted to take into a recreation yard against prison rules.

The 38-year-old Pruett was already serving a 99-year sentence for a neighbor's killing near Houston when he was convicted in Nagle's death.